Wildfires in South Africa may be having a positive effect on the environment. They are apparently helping cool the surrounding areas by making clouds that reflect radiation from the sun.
Results of a new study carried out by the University of Wyoming suggest that this unexpected cooling effect could counter global warming. Previous studies on smoke in the atmosphere had pointed to it having an overall negative effect on warming because smoke absorbs light that clouds normally reflect, noted a release by the University.
However, smoke from South African wildfires, drifting over the south-east Atlantic Ocean, "significantly enhances" the brightness of the clouds there. This, the researchers found, actually helps cool Earth because more light reflected away from the atmosphere equals less heat reaching the surface.
"If you change the particles, you are changing the composition of the cloud," said Xiaohong Liu, a UW professor in the Department of Atmospheric Science and the Wyoming Excellence Chair in Climate Science.
"For our study, we found the smoke comes down and can mix within the clouds. The changed clouds are more reflective of sunlight. Brighter clouds counteract the greenhouse effect. It creates cooling."
On how it works, the scientists explained that smoke and clouds are actually a lot closer than what was once believed. This proximity also means tiny aerosol particles from smoke can speed up the formation of droplets in the clouds.
"Our group is the first to quantify this brightening effect," Liu said. "This (smoke aerosols in clouds) reflects more solar radiation to space, which results in less solar radiation reaching the Earth's surface. This creates a cooling effect."
Liu went on to explain that carbon dioxide dumped into the atmosphere because of human activity since the dawn of the industrial revolution has a "greenhouse effect" of 1.66 watts per square meter, and it is spread out evenly throughout the globe. The biomass smoke from South Africa, on the other hand, produces 7 watts per square meter of cooling over the south-east Atlantic in the wildfire season from July to October every year.
Wildfires are a regular occurrence in that part of the world, noted the release. Some of them are natural, while others are started to clear out land for farming. They are so big that they can actually be seen in satellite images of the region.
Smoke from the continent is carried west through to the south-east Atlantic Ocean where they interact with clouds about a kilometer over sea level.
While this study was concentrated to only one part of the planet, researchers plan on taking this model and applying it to Earth's entire climate system while also including other sources of carbon dioxide like power plants, automobiles, deserts and oceans in the near future.
